On Mon, Oct 16, 2017 at 02:24:40PM +0100, Mark Rutland wrote:
> The arm64 VDSO Makefile explicitly disables gcov; a practice we seem to
> have inherited from other VDSO Makefiles.
>
> The arm64 VDSO is written entirely in assembly, so this is not
> necessary. Further, if the VDSO were written in C it would be necessary
> to disable all other instrumentation, and this alone would not be
> sufficient.
Evidently, I haven't looked hrough the history thoroughly enough. It
turns out that this was deliberately added in commit:
543097843ca7c9ac ("arm64: build vdso without libgcov")
... this is necessary because we use the compiler to do the actual
linking. That causes us to have -lgcov in the compilr flags, and the
link can fail.
Please ignore this patch for now.
Thanks,
Mark.
> This patch remosves the redundant GCOV option for now.
>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Reported-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> ---
> arch/arm64/kernel/vdso/Makefile | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> index 62c84f7cb01b..350190b749dd 100644
> --- a/arch/arm64/kernel/vdso/Makefile
> +++ b/arch/arm64/kernel/vdso/Makefile
> @@ -15,9 +15,6 @@ ccflags-y := -shared -fno-common -fno-builtin
> ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \
> $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
>
> -# Disable gcov profiling for VDSO code
> -GCOV_PROFILE := n
> -
> # Workaround for bare-metal (ELF) toolchains that neglect to pass -shared
> # down to collect2, resulting in silent corruption of the vDSO image.
> ccflags-y += -Wl,-shared
> --
> 2.11.0
>
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